Vapor lamp



Aug. 29, 1-939. D s, s m 2,171,237

VAPOR LAMP Filed Oct. 20, 1934 I NVENTOR )2 s 6M577/V ATTORN the type emploing an incandescent cathode and Patented Aug. 29, 1939 UNITED .sr -ss PATENT OFFICE Daniel S. Gurtin, Bloomfield, N. 1., asaignor, by mesne assignments, to Westinghouse Electric and Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 20, 1934, flerialNo. 749,197

3 Claims. cl. 110-122) This invention relates to a discharge device of 1 solid electrodes operating in an ionizable medium and, more particularly, to devices operating in a medium comprising a metallic vapor;

, In devices of the character to which the pres:

' ent invention relates, it has been the practice to use a metallic-vapor such as sodium or the like,

together with a small amount ofa rare gas such as argon or neon to promote starting. A device of this character is' shown and described in copending application Serial Number 668,506 filed when lamps of the above character are used for outdoor lighting, the variation in the temperatures to which they are subjected causes a variation in the operatlton of the device. If the temperature falls too low the vapor condenses, often causinga termination of the discharge.

It is an object of the present invention to provide a lamp of the-above character with means 1 for maintaining the lamp at operating temperature.

Another object of the invention is to provide a discharge lamp-oi the metallic vapor type in which current flowing through the discharge is utilized to heat the vapor.

Another objectofthe invention is to provide a discharge device of the above, character in which the internal circuit includes a heater element inparallehwith current flowing through odes and a cathode and resistant heaters in series the discharge.

Another object of the invention is to provide a discharge device including a plurality of an- Fig. 3 is a sectional view taken on line III-III in Fig.1, in the direction oi the arrows;

Fig. 4 is a view showing the same general construction as that shown in Fig. 1 but includes a center tap on the cathode connecting with a transformer for the purpose of including a choke coil as shown diagrammatically together with the transformer.

Although the present invention may be employed in various forms of discharge devices, the selected embodiment of the invention comprises a bulb l having a; neck portion ll arranged to lit a flare tube l2 integral with an outer bulb or chamber I9.

A clamping ring 14 is employed in conjunction with a resilient collar I! to hold the bulb ill in position.- The flare tube l2 may be provided with the usual press I8 and exhaust tube l'l'. Extending from the press are support rods i8 and I9 connected to the terminals of a cathode 2i. The cathode may be in the form of a helical coil comprised of the tungsten or other refractory metal and may have a coating of electron emissive material sprayed or otherwise deposited thereon. The electron emissive material may be a mixamyl acetate binder. A coating of barium oxide has been found satisfactory. The coil 2| may be provided with a core of barium silicate instead of the coating material or both may be used.

Lead wires 22 and 29 extend through the press and are electrically connected with conductive support members 24 and 25 respectively. Electrically connected with the conductor 24 isan anode 26 in the form of a hollow cylinder disposed at the lower end of the bulb and preferably coaxial therewith. Electrically connected to an end of the support 25 is a similar anode 2l disposed at the other end of the bulb and preferably coaxial with the anode 26. An insulative sleeve 28 may be employed to enclose the conductive support 25. Between one terminal of the cathode 2i and the anode 26 is connected a resistance element 29 and between the other terminal of the cathode and the anode 21 is connected a resistance element 36. The elements 29 and 3| may be in the form of helical coils of refractory material such as tungsten and of suitable proportions as give the desired resistance, so that when a discharge occurs most of the current will take the path of the discharge. The adjacent ends of the elements 29 and 3| are desirably respectively connected to diagonal extensions on the rods l9 and i9, whereby they are properly spaced from the cathode 2|. Thus said elements are 25 ture of carbonates in the usual nitro-cellulose brought into a common axial plane and maintained substantially parallel to one another, while angularly disposed with respect to the bulb axis. A disk 32 of asbestos or other suitable material is disposed in the neck portion of the bulb II) to keep the vapor from portion of the stem.

A lamp constructed, as described above, may be provided with the usual screw threaded base to which the lead wires 22 and 23 may be connected in the manner employed i'or standard lamps.

When in operation current normally flows through lead 22, resistance element 29, cathode 2|, resistance element 3| and back through lead 23. The bulb Ill may have deposited therein a quantity of vaporizable metal such as sodium or cadmium and a small amount of rare gas. When current flows through the heater elements, which are of relatively high resistance, they become heated and the cathode being in series with the heater elements is also heated to an electron emitting temperature. By reason of the rare gas content, an initial. discharge is caused in the rare gas which, together with the heater elements operate to vaporize the sodium or other material creating a vapor which becomes ionized. This results in an appreciable discharge between one anode and the cathode during the opposite cycle, when the lamp is operated on alternating current. As the discharge increases, the cathode is heated by bombardment and reaches a temperature at which it becomes highly electron emissive. When the device is in full operation, the main current flow is through the discharge by reason of the resistance heater elements.

Although the heater elements take suilicient current to maintain them at a temperature suflicient to keep .the sodium from condensing at low temperatures, they do not, however, pass sufiicient current to reduce the discharge current flow to the point at which it would not be effective to keep the lamp operating at the required lumens per watt. f

For the purpose of smoothing out the alternating current; the cathode 2| may, as shown in Fig. 4, have a central connection 33 in the form of a conductor '34 which connects with one end of the choke coil or condenser 35, the opposite end of which connects with a central tap 36 on the secondary 31 of a transformer 38. With the construction as shown in Fig. 4, the operation of the lamp is less subject to flicker.

Although the present device may-be used on commercial lines for series burning where a constant current supply is provided, it is obvious that it may also be used onsuitable line voltage with a contact with the cool I .7 without departing from the spirit'and scope of the given current and that a suitable ballast resistance or other current regulating means may be employed.

A preferred embodiment of the invention is shown and described herein, but it is to be understood that modifications may be made therein appended claims.

I claim? a 1. In combination with an electrical discharge device comprising an elongated bulb, an anode in said bulb at each end, a cathode disposed betwen said anodes, and heating means electrically conmeeting said cathode and anodes, of means for energizing said device comprising a transformer the secondary terminals of which are connected to said anodes, and stabilizing means, one termi- I nal of which is connected to a central tap on said secondary, and. the other terminal of which is connected to a central point of said cathode, for minimizing flicker of said device.

2. An electrical discharge device comprising a bulb, a quantity of sodium in said bulb, a hollow cylindrical, anode disposed adjacent each'end of said bulb, said anodes being axially disposed with respect to one another, a thermionically active cathode formed as a helix of wire coated with electron emission material, disposed substantially midway between and with its axis extending transverse to the axis of said anodes, means extending from one end of said bulb for supporting said anodes and cathode, said anode supporting means serving to conduct current thereto, and a helical wire coil electrically connected to the cathode and each anode and extending therebetween to conduct current to said cathode from said anodes, toheat the former to electron emitting temperature, and maintain the sodium vaporized to a suflicient extent under varying conditions of operation.

3. A discharge device comprising a bulb, a cathode, a pair of anodes disposed substantially coaxial with one another, one on each side of said cathode, a support for each end-of the oathode, a lead extending to each anode, a resistance heater element extending along the discharge path between each anode and the cathode, said heater elements lying approximately in a, plane axial of the anodes, the anode-adjacent end of each element being disposed approximately axial its anode and electrically connected thereto, the cathode-adjacent ends of the elements being laterally spaced from each other and said cathode, and connected to extensions from the oathode and supports. I

DANIEL S. GUSTIN. 

